Dampers have long been used in a variety of fluid handling applications to control the flow of various types of fluids. Typical uses of industrial dampers include the handling of process control fluids, the handling of fluids in power plants, and the handling of high speed fan discharge streams. Industrial dampers are usually subjected to relatively high pressures and must have considerable strength in order to be capable of withstanding the forces that are applied to them.
The damper construction normally includes a rigid frame which defines a flow passage controlled by a plurality of damper blades that each pivot between open and closed positions about a respective axle. The blades are often interconnected by a linkage which moves all of them in unison to control the fluid flow rate in accordance with the damper blade position. Although flat damper blades are often used, it has long been recognized that airfoil shapes can be used to enhance the fluid flow. Airfoil blades are thickest in the center at the pivot axis and taper toward each edge to present an aerodynamically efficient shape which minimizes turbulence and other undesirable effects such as noise generation and stresses on the flow passage and other components of the fluid handling system.
In the past, damper blades have been formed by bending multiple sheets of steel and joining them together to form an airfoil shape. Typically, in a separate step, a bead of silicone or other sealant may be manually deposited at the respective ends of each blade to provide for an air tight seal between the damper blades when in a closed position. In a further separate step, a bracket is mounted to each end of the blade, which is necessary to locate and accommodate an axle on which each blade pivots. As will be readily appreciated, however, existing airfoil blades are very time consuming and tedious to manufacture, requiring numerous and separate manual steps. In addition, existing blades often require additional strengthening ribs to bolster the blade under high speed flow, which may further increase the cost and labor involved.
Accordingly, it is desirable to provide an airfoil blade assembly that is easier, more cost effective, and less labor-intensive to produce than existing blades.